I. Technical Field
The present invention relates to a planning method and apparatus for peritoneal dialysis and hemodialysis hybrid remedy.
II. Description of Related Art
There are presently about 200,000 patients with chronic renal failure in Japan. Of them, 92% to 93% receive a treatment using hemodialysis while the remaining 7% to 8% being treated with peritoneal dialysis.
“Dialysis” here means a process of removing molecules from body fluid due to a concentration gradient by filtering it across a membrane, making use of different molecular weights. Thus, this process assists impaired renal function of the patients by transferring various substances which are accumulated in the body through metabolic activities—solutes (such as urea (U) as a uremic toxin and creatinine (Cr)), electrolytes (Ca2+, Cl−, Na+, and K+), excess water and the like—out of the body fluid into a dialysis solution, and by then discharging the dialysis solution from the body as drained fluid. Two distinguished modalities used for dialysis treatment are hemodialysis (HD) and peritoneal dialysis (PD). Hemodialysis involves filtration of blood using a dialysis solution while peritoneal dialysis is a procedure in which a dialysis solution is infused into the peritoneal cavity. Conventionally, either one of the dialysis procedures has been applied to the patients.
In recent years from 1990's onward, a hybrid remedy with peritoneal dialysis and hemodialysis (PD-HD) has gradually been applied to clinical practice in Japan, coupled with coverage for dialysis treatment by health insurance. In the hybrid remedy, PD is employed with the purpose of alleviating a burden on the patients and preferably making use of the residual renal function as much as possible while HD is being concomitantly used as an auxiliary measure.
A PD system in which a condition of a patient's peritoneal function is simulated by a computer has recently been developed (see Japanese Laid-Open Patent Application Publication No. 2000-140100). This PD system enables testing aspects of peritoneal function, such as the rates of solute removal and transperitoneal water removal, by computing Pyle-Popovich's mathematical model-known as a macroscopic model of PD—from patient's data (the concentration of each solute, the volume of water removal and so on, included) obtained by using PET (Peritoneal Equilibration Test, 1987). Herewith, a PD schedule for a week, for instance, can be worked out.
However, the above PD system is specialized to plan a schedule for PD, and a problem remains that dialysis planning for a PD-HD hybrid remedy is difficult to establish. That is, although there are conventionally modality-specific parameters for PD and HD, respectively (clearance, the number of dialysis sessions, etc.), when it comes to dialysis planning for the hybrid remedy, a parameter shared between these two modalities is not yet known, and therefore creating the dialysis schedule is comparatively difficult. For this reason, the establishment of a planning method allowing to work out an accurate dialysis schedule for the hybrid remedy has been called for.